1 Chronicles 19:9-15

children of Ammon . . . put the battle in array before the gate of the city—that is, outside the walls of Medeba, a frontier town on the Arnon.

the kings that were come were by themselves in the field—The Israelitish army being thus beset by the Ammonites in front, and by the Syrian auxiliaries behind, Joab resolved to attack the latter (the more numerous and formidable host), while he directed his brother Abishai, with a suitable detachment, to attack the Ammonites. Joab's address before the engagement displays the faith and piety that became a commander of the Hebrew people. The mercenaries being defeated, the courage of the Ammonites failed; so that, taking flight, they entrenched themselves within the fortified walls.